Deck 19: Electron Transport and Oxidative Phosphorylation

Question 1

Which of the following regarding redox reactions is NOT correct?

A)Standard free energy change for a redox reaction is related to the standard reduction potential.
B)Standard free energy change for a redox reaction is related to the number of electrons transferred.
C)For redox reactions with negative standard reduction potentials,standard free energy change is negative.
D)Redox reactions must occur in pairs,where the total number of electrons involved in the oxidation equals the total number involved in the reduction.

Answer 1

C

Question 2

Which of the following cytochromes receives the electron transferred from UQH₂ to the Rieske protein?

A)cyt c
B)cyt bH
C)cyt bL
D)cyt c1

Answer 2

D

Question 3

Which of the following classifies the phosphorylation of ADP that is NADH-dependent?

A)oxidative
B)electron
C)proton-gradient
D)substrate-level

Answer 3

D

Question 4

Which of the following is a mobile electron carrier?

A)UQ
B)[FMN]
C)Complex I
D)Complex III

Question 5

Which of the following components is a 2-electron donor?

A)FAD
B)Fe-S
C)NADH
D)cyt c

Question 6

Which of the following metabolic pathways is NOT linked to the electron-transport chain through Complex I,which accepts electrons from NADH?

A)gluconeogenesis
B)glycolysis
C)TCA cycle
D)fatty acid oxidation

Question 7

Which of the following components part of Complex I?

A)[FAD]
B)cytochrome c
C)Fe-2S clusters
D)4Fe-4S clusters

Question 8

NADH is a strong reducing agent.What kind of reduction potential does it possess?

A)large positive value
B)large negative value
C)small positive value
D)small negative value

Question 9

Which of the following is a characteristic of inner mitochondrial membranes?

A)They contain specific receptor proteins.
B)They fold into cristae.
C)They contain porin in high concentration.
D)The membrane lipids have mostly saturated fatty acids.

Question 10

Which of the following is a property of coenzyme Q?

A)It is hydrophilic.
B)It cannot diffuse easily in the membrane.
C)It has 3 oxidation states.
D)It shuttles from Complex I and Complex II to Complex IV.

Question 11

Which of the following is the source for the energy that drives ATP synthesis?

A)the proton gradient
B)NAD⁺ and FAD
C)the electron gradient
D)molecular oxygen

Question 12

Which of the following takes place in the Q cycle?

A)Two protons are pumped into the matrix.
B)Electrons are transferred from bH to bL.
C)Two electrons are passed from bL to UQ.
D)One UQH₂ is returned to the pool.

Question 13

Which of the following complexes reduces molecular oxygen?

A)Complex I
B)Complex II
C)Complex III
D)Complex IV

Question 14

Which of the following is the common product produced by Complex I and Complex II?

A)FAD
B)reduced coenzyme Q
C)NAD⁺
D)reduced O₂

Question 15

Which of the following reaction classifications has a standard reduction potential that is positive under standard conditions?

A)restrained
B)structured
C)planned
D)spontaneous

Question 16

Which of the following enzymes is NOT a flavoprotein?

A)NADH-CoQ reductase
B)succinate dehydrogenase
C)coenzyme Q-cytochrome c oxidoreductase
D)fatty acyl-CoA dehydrogenase-transferring protein

Question 17

Which of the following is need for the spontaneity of a redox reaction?

A)electron flow
B)concentration of the species being oxidized
C)concentration of the species being reduced
D)standard reduction potential

Question 18

Which of the following correct regarding redox couples is NOT?

A)Standard reduction potentials are measured relative to a standard hydrogen cell (H⁺/H₂).
B)For cells in which electrons flow toward the sample half-cell,the reduction potential is positive.
C)A redox couple consists of a substance being oxidized and the substance oxidizing it.
D)A half-reaction involving the loss of electrons is an oxidation reaction.

Question 19

Which of the following components is NOT membrane bound?

A)cytochrome ? /? ₃
B)cytochrome c
C)cytochrome c₁
D)coenzyme Q

Question 20

Which of the following resides in the mitochondria?

A)enzymes for glycolysis
B)adenylate cyclase
C)the pentose phosphate pathway
D)the electron transport complexes

Question 21

Which of the following is the final electron acceptor in the electron-transport chain?

A)molecular oxygen
B)H₂O
C)cytochrome c
D)NAD⁺

Question 22

Which of the following is a characteristic of the F₁ unit of ATP synthase?

A)The a- and b-subunits are not homologous
B)It consists of 6 different kinds of subunits.
C)It catalyzes ATP synthesis but not ATP hydrolysis.
D)The b-subunits have catalytic sites for ATP synthesis.

Question 23

Which of the following is a characteristic of the binuclear centre of Complex IV?

A)Fe-S is a component.
B)Water is needed here.
C)Cyt c is a component.
D)Two electrons are transferred to bound O₂.

Question 24

Which of the following molecules is the electron donor to Complex III?

A)cytochrome c
B)UQH₂
C)NADH
D)FADH₂

Question 25

Which of the following is a property of ATP synthase?

A)The F1 subunit is attached to the peripheral membrane protein F0.
B)The ring of c subunits forms a rotor with respect to the alpha subunits.
C)The F0 subunit is hydrophilic.
D)Alpha-subunits have the catalytic site for ATP synthesis.

Question 26

Which of the following c-subunit residues of ATP synthase are proton neutralized during ATP synthesis?

A)Ser
B)Asp
C)Arg
D)Glu

Question 27

How many electrons are required for the complete reduction of 1 molecule of oxygen gas?

A)2
B)3
C)4
D)6

Question 28

Which of the following is NOT a characteristic of proton gradient-driven enzyme conformational change in ATP synthase?

A)binding of substrates
B)catalytic cooperativity between subunits
C)conformational change in the b-subunits releasing ATP
D)rotation of (ab)3 complex relative to a fixed b-subunit

Question 29

Which of the following is NOT a single-electron carrier?

A)UQH₂
B)cyt bL
C)cyt bH
D)cyt c1

Question 30

Does electron transport stop if rotenone is added? Which of the following explains the reasoning?

A)Yes,there is not an electron source.
B)No,rotenone is not strong enough to inhibit all of the electron-transport chain.
C)No,there is still a source of electrons from Complex II.
D)Yes,rotenone inhibits Complex III;therefore,electrons cannot be passed on.

Question 31

How many protons are released by Complex III on the intermembrane side for each pair of electrons that pass through the Q cycle?

A)1
B)2
C)3
D)4

Question 32

Which of the following complexes does NOT translocate protons in the inner mitochondrial membrane?

A)Complex I
B)Complex II
C)Complex III
D)Complex IV

Question 33

Which of the following is a characteristic of cyt c?

A)It accepts electrons from cyt bH.
B)It is globular with planar heme group near the centre of the protein.
C)It is water insoluble.
D)It is zinc coordinated with histidine nitrogen and methionine sulphur atoms.

Question 34

Which of the following components is NOT part of cytochrome c oxidase (Complex IV)?

A)CuA
B)CuB
C)cyt c1
D)cyt a3

Question 35

Which of the following does NOT transfer electrons to the UQ/UQH₂ pool?

A)Complex I
B)fatty acyl-CoA dehydrogenase
C)Complex IV
D)sn-glycerophosphate dehydrogenase

Question 36

Which of the following is a characteristic of the binding charge mechanism?

A)Energy-driven conformational changes convert O-sites to L-sites.
B)One site is empty (L-sites).
C)One site contains ADP and Pi (O-sites).
D)T-sites become O-sites.

Question 37

Which of the following subunits in ATP synthase is anchored to the rotor?

A)a
B)b
C)g
D)c

Question 38

Which of the following is another term used to define Complex II in the electron-transport chain?

A)cytochrome c oxidase
B)NADH-CoQ reductase
C)succinate-CoQ reductase
D)cytochrome bc1 complex

Question 39

Which of the following complexes will be affected if rotenone is added?

A)Complex I
B)Complex II
C)Complex III
D)Complex IV

Question 40

Which of the following is included in the model of electron transport?

A)protons driven into the matrix
B)mobile coenzyme Q releasing electrons
C)cyt c moving in the intermembrane space
D)proton gradient reduced leading to loss of ATP production

Question 41

Which of the following is a characteristic of the malate-aspartate?

A)Electrons of cytosolic NADH are translocated to mitochondrial NADH.
B)OAA is translocated to the inner mitochondrial membrane.
C)There is only one malate dehydrogenase enzyme.
D)The reactions are irreversible.

Question 42

Which of the following is NOT correct regarding the glycerophosphate shuttle?

A)Glycerol-3-phosphate is translocated across the inner mitochondrial membrane into the matrix.
B)There are 2 distinct forms of glycerol-3-phosphate dehydrogenase in cells with this shuttle.
C)It results in the net transfer of electrons to the electron-transport chain from NADH in the cytosol.
D)Electrons derived from this shuttle enter the electron-transport chain at UQ.

Question 43

Which of the following is an inhibitor of Complex IV?

A)rotenone
B)oligomycin
C)antimycin
D)cyanide

Question 44

In which of the following tissues does thermogenin (UCPI)create a passive proton channel through which protons flow from the cytosol to the mitochondrial matrix?

A)myelin
B)brown adipose
C)nerve
D)cardiac

Question 45

Which of the following molecules is least likely to be transported across the inner mitochondrial membrane?

A)NADH
B)citrate
C)pyruvate
D)malate

Question 46

Which of the following percentages of the proton gradient energy to synthesize and transport ATP to the cytosol is involved in ATP-ADP transport?

A)10%
B)15%
C)25%
D)50%

Question 47

Which of the following explains why bacteria and other prokaryotic cells have the capacity to get more ATP/glucose oxidized than eukaryotic cells?

A)They are simpler and have less going on.
B)They do not have to use shuttles to reoxidize reduced nucleotides.
C)They do not have to translocate ATP-ADP across the mitochondrial membranes.
D)They use an electron-transport chain that translocates more protons.

Question 48

Which of the following defines the P/O ratio?

A)Pi uptake per oxygen atom by mitochondria
B)molecules of phosphate released from ATP per oxygen utilized by muscle tissue
C)ratio of atoms of phosphorus to oxygen in phosphate (Pi)
D)molecules of ATP formed per 2 electrons flowing through electron-transport chain

Question 49

Which of the following cytochromes,in the ferric form,do cyanide and azide bind tightly to?

A)cyt c
B)cyt a3
C)cyt bL
D)cyt bH

Question 50

Which of the following is NOT a property of the mitochondrial glycerol-3-phosphate dehydrogenases?

A)The mitochondrial enzyme family has bound coenzyme Q.
B)They work to carry electrons into mitochondria.
C)One is located in the inner mitochondrial membrane.
D)There exists an FAD-dependent mitochondrial enzyme.

Question 51

Which of the following is a part of apoptosis?

A)deactivation of caspases
B)mitochondrial membrane permeabilization (MMP)
C)closure of the mitochondrial outer membrane protein-permeable pores
D)a series of anabolic reactions

Question 52

Which of the following statements is a characteristic of the glycerophosphate shuttle?

A)It shuttles NADH across the mitochondrial membrane to yield 2.5 ATP/ADH.
B)It shuttles "NADH electron equivalents" across the mitochondrial membrane to yield 1.5 ATP/NADH.
C)It operates efficiently only when the [NADH] in the cytoplasm is higher than in the matrix.
D)The molecule malate is a key component in the shuttle process.

Question 53

Which of the following enzymes catalyzes the reaction below?
Dihydroxyacetone phosphate (DHAP)+ NADH à NAD⁺ + glycerol-3-phosphate

A)glycerol-3-phosphate dehydrogenase
B)triose phosphate isomerase
C)DHAP dehydrogenase
D)glycerol-3-phosphate reductase

Question 54

Which of the following does NOT occur in the malate-aspartate shuttle?

A)OAA is transaminated to aspartate.
B)OAA is reduced to malate.
C)Malate is oxidized to OAA.
D)Aspartate is translocated to the matrix.

Question 55

Which of the following is a property of uncouplers?

A)They enhance the proton gradient.
B)Electron transport continues.
C)ATP/ADP ratio increases.
D)Water is produced.

Question 56

Which of the following is the effect of adding oligomycin and then 2,4-dinitrophenol to respiring mitochondria?

A)Electron transport speeds up and ATP synthesis stops.
B)Electron transport continues and ATP synthesis continues.
C)Electron transport stops and ATP synthesis stops.
D)Electron transport stops and ATP synthesis continues.